Heavy alcohol consumption among adolescents is a fundamental public health threat. There is evidence that heavy alcohol use and alcoholism impair intestinal absorption of folate (vitamin B9), and promotes renal and hepatic folate excretion. Therefore, adolescent girls may face additional risks from heavy alcohol consumption. Inadequate folate status contributes to a host of poor birth outcomes and adverse consequences later in childhood. The proposed prospective epidemiological study will recruit a stratified quota sample of White, African American and Latina (N=455) adolescent girls aged 14 - 18 years. Participants will be monitored over a 4-week period with assessments including weekly collecting of dried blood spot samples (to monitor folate) and continuous transdermal assessment of blood alcohol level. Collected data will be used to achieve three primary specific aims: 1) delineate racial and ethnic variation in the frequency and intensity of alcohol intoxication over time among 14-18 year-old girls, controlling for important familial influences on alcohol use; 2) describe racial and ethnic variation in folate status over time, controlling for dietary habits and important familial influences; and 3) delineate variation in folate status by alcohol intoxication, and determine if folate status is depleted following heavy episodic drinking events. Accomplishing these aim is significant because there are persistent racial and ethnic disparities in poor birth outcomes among women of color, and the role of earlier alcohol behavior in these disparities is ambiguous. This project therefore addresses a critical gap in the literature by expanding knowledge about the potential role heavy alcohol use and subsequent implications for folate status may play in creating racial and ethnic inequities in poor birth outcomes including birth defects. The proposed study is innovative in its prospective, community-based design, its focus on adolescent girls, its objective assessment of alcohol use through continuous transdermal assessment, and its rigorous field assessments of serum folate through the collection of dried blood spot samples. Accomplishing the goals of this study will allow for targeted identification of potential causes of several pregnancy-related problems and birth defects. Such information can be helpful in reducing health disparities related to pregnancy and childbirth.